This application claims the priority of German Patent Application No. 198 05 515.3, filed Feb. 11, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an obstacle recognition system in a motor vehicle and, more particularly, to an obstacle recognition system in a motor vehicle with an electronic control device and sensors for detecting the distance of an obstacle within a predetermined area.
An obstacle recognition system of this kind is known for example by the term "Park Distance Control" (PDC) for BMW vehicles (cf. brochure entitled "The BMW 5 Touring," Accessories, 1995, Page 10, Point 2). This known PDC obstacle recognition system has an electronic control device and sensors to detect the distance from an obstacle within a specified area. Sensors of this kind can be provided, for example, in the rear area as well as in the front area to facilitate parking. In the known PDC obstacle recognition system, four sensors in the form of ultrasonic sensors are integrated at least into the rear bumper, which can be activated automatically for example when the reverse gear is engaged. By means of warning pulses with a changing interval, the current distance to an obstacle behind the vehicle is signaled. The specified area within which the obstacle recognition system operates is defined in particular by the lobe-shaped acquisition areas of the sensors.
Problems are created in a PDC obstacle recognition system activated in this way by various parts mounted on the vehicle, which may be located in the acquisition area of the sensors, and therefore basically could be detected as obstacles. One such part is a trailer hitch for example. If the trailer hitch is supporting a trailer which is also connected electrically with the vehicle, a signal to suppress the activated obstacle recognition system can be delivered by this electrical connection.
The goal of the invention is to suppress a false alarm from an obstacle recognition system when parts are mounted on the vehicle, especially a trailer hitch, even when the trailer is not connected.
This goal is achieved by providing an obstacle recognition system in a motor vehicle with an electronic control device and with sensors for detecting the distance of an obstacle within a predetermined area. The control device, in a defined partial area of a part possibly mounted on the vehicle which could be recognized by a sensor as an obstacle, in the event of recognition of an actual obstacle in this partial area, in a first step determines the distance of the obstacle and in a second step checks to determine whether this distance is changing.
In a preferred embodiment, the alarm that is usually triggered as a function of the distance to the obstacle is suppressed if the distance to the obstacle detected in the defined partial area does not change.
It is essential to the present invention that the control device, in a specified partial area in which a part might possibly be connected to the vehicle that could be detected as an obstacle by a sensor, in the event of an actual obstacle being detected in this partial area, determine in a first step the distance of the obstacle from the vehicle itself. In a second step, the control device checks whether the distance changes, for example during a movement of the vehicle or after a predetermined time. The invention is based on the fact that when parts (mounted on the vehicle) are detected as obstacles, the distance does not change during a movement of the vehicle. However, during a movement of the vehicle or the obstacle, the distance from obstacles located outside the vehicle does change. As a result of the ability to distinguish between obstacles that are detected, an alarm from the obstacle recognition system can be suppressed for example when the detected "obstacle" turns out to be a part.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.